In a computer system, a card edge connector is used for insertion of an electronic card, such as a memory module. The card edge connector mainly functions to input a signal into the electronic card or output a signal from the electronic card to other element of the computer system. Therefore, the electronic card preferably can be reliably inserted into the card edge connector so as to allow the computer system to operate properly. In addition, when an electronic card is inserted downwardly into card edge connector along a vertical or up-down direction, the card edge connector must also tolerate repeatedly engagement with the he electronic card without deforming. It turns out that traditional card edge connectors do not address these issues in a desirable manner. Chinese utility model patent application CN97214647.4 (corresponding to Taiwanese patent application TW85220265 and U.S. Pat. No. 6,027,358) discloses a connector with a card retention means, the connector comprises an insulating body, a latching means and a card retention means. The insulating body is provided with a slot, a rail and a mounting portion. The slot is configured to receive a card. The rail is used to receive a side edge of the card. The mounting portion is used to mount the card retention means. The latching means is mounted to the insulating body so as to latch the card. However, the card retention means is mounted above a top end of the rail, and two elastic arms of the card retention means are completely exposed relative to the rail. Consequentially, when a card is inserted into the card slot in a vertical direction the card can often directly collide with a top portion of the elastic arm and damage the elastic arm so as to cause the connector to improperly function. It is even possible, in certain instances, for the elastic arm to be deformed when the card is attempted to be inserted into the card slot so that it elastic arms get pressed into into a receiving path of the rail so as to block further insertion of the card. Thus, certain individuals would appreciate an improved card edge connector system.